May, 1914.] Stai'ch Reserve in Birch and Maple. 317 



STARCH RESERVE IN RELATION TO THE PRODUCTION 



OF SUGAR, FLOWERS, LEAVES, AND SEED IN 



BIRCH AND MAPLE. 



Forest B. H. Brown. 



American scientific literature is lacking in a standard treatment 

 of subjects dealing with the stored reserve in our fitiit and forest 

 trees, such as have been made by Busgen in his "Waldbaume," 

 and in other still more recent GeiTnan publications. The work of 

 Jones and others of Vermont (Bull. 103, 1903) contains much 

 infonnation on the maples. But this work does not furnish the 

 drawings essential to a clear presentation of starch storage, 

 and the description is inadequate. Even in this bulletin, no at- 

 tempt is made to show in what way the vast amount of potential 

 energy represented in the stored starch is used, otherwise than in 

 the production of sugar, while the authors themselves conclude 

 that rarely is there used, in this way, more than 4% of the total 

 starch stored in a tree. 



This fact, together with the very conflicting statements made 

 in the available published records, has led the writer to publish 

 these few preliminary studies. The ease with which such studies 

 may be carried on, together with their direct bearing upon many 

 of the vital problems of forestry and various branches of agricul- 

 ture, would suggest their general fitness to be included in the bot- 

 any laboratory course, even in the high school possessed of only 

 one microscope. 



Data for the present paper were taken from selected trees of 

 birch and maple growing on the Ohio State University campus. 

 Particular attention was given to a sugar maple, Acer saccharum 

 Marsh., north-west of the law building. From a 1-year twing of 

 this tree, a cross-section 20 mic. in thickness was cut April 1, by 

 means of a sliding microtome, stained one minute in iodine, and 

 then mounted in glycerine. A camera drawing was made, Fig. 1, 

 the magnification being shown by the accompanying scale. vSimi- 

 larly, a section was cut from a root 8 mm. in diameter, Fig. 2. 

 The granules of starch have been indicated in solid black. In the 

 stem the starch grains are shown in the medullary rays (u. m. and 

 b. m.), wood parenchyma fw. p.), and in all the primary xylem 

 tissues except the vessels. The wood fibres were empty in all the 

 sections studied; but in the root, the wood fibres, as well as the 

 wood parenchyma and medullary rays, are filled. Also, many of 

 the tissues of the bark, both of stem and root, contain starch. 

 Beginning with the first layer inside the cork, they are, in order, 

 as follows: the periderm, collenchyma, thin walled parenchyma, 

 bast parenchyma, and bast rays. The maple, however, con- 

 tained less starch at this period in the bark tissues than the birch 



